The chilling facts about frostbite

Q: It has been freezing and I work outside a lot. How will I know if I am starting to get frostbite?

Dr. Jeff Hersh

Q: It has been freezing and I work outside a lot. How will I know if I am starting to get frostbite?

A: Frostnip is a non-freezing injury to the skin, but if the skin or other tissues actually freeze, we call it the more severe condition: frostbite. So it is reasonable to consider frostnip a precursor to frostbite.

Frostnip can present with red or even yellow-gray skin that is soft and resilient (the skin is not frozen), and is usually not painful. Many of us have experienced this, especially on our cheeks, while outside on a cold, wintry and windy day. The affected area usually recovers quickly and completely once it is rewarmed. If, instead, it is subjected to ongoing cold, frostbite can occur. Frostbitten skin or body tissue is actually frozen and the area will feel cold and hard, like wood.

Since the blood brings heat (and oxygen and nutrients) to the body, anything that decreases blood supply, such as smoking or diseases like diabetes, will increase the chances of getting frostbite. Greater cold exposure, such as submersion in cold water or prolonged cold exposure, will increase the risk as well. Of course, once the area is frozen no further blood supply can get there, so there is no further warming and the freezing will only worsen.

From this discussion it will not surprise you to learn that 90 percent of frostbite affects the feet and hands. The remaining cases are typically of the ears, nose and cheeks, although other body parts might be affected.

The best way to prevent frostbite is to prevent prolonged exposure to the cold. Wear appropriate clothing for the conditions and pay special attention to covering hands and feet. Tight-fitting shoes that may decrease blood supply should be avoided. And, of course, be sure to keep dry.

Once frostbite has set in, the goal is to prevent or minimize permanent tissue damage and to salvage any of the areas that can be saved.

The extent of tissue injury is related to how long the area is frozen and not by how frozen it gets, so rewarming should be done as early as possible. However, tissue injury can be exacerbated if rewarming is too slow. It can also be made worse if the frostbit area is partially rewarmed and then refreezes.

Therefore, frostbite should be rewarmed rapidly, typically by submerging the area in warm (104-108 degrees) water for 15-30 minutes. This can hurt, so pain medication is usually necessary.

Patients with severe frostbite usually need to be admitted to the hospital. Evaluation to decide if the affected area is viable and will recover, or will have to be amputated, should be made by an experienced surgeon during the hospitalization; it cannot be predicted based solely on the initial presentation.

The treatment of frostbite in the field is more problematic. As noted above, partial or incomplete rewarming can worsen the tissue damage, so if complete rewarming cannot be done, the area should be splinted and padded to minimize trauma and the patient transported for definitive care. Rewarming should be avoided if it is likely to cause an area to be thawed just to have it refreeze, or if it will cause excessive delays in obtaining further treatment. Rubbing the affected area - like they too often show on TV - is NOT appropriate since it can worsen tissue damage.

The throbbing pain in the rewarmed and salvaged areas of frostbite can persist for days or even weeks. Patients with frostbite of their extremities who do not require amputation may experience sensation changes in the affected areas including tingling, burning and numbness that can last for years and even for life. There is often a heightened sensitivity to cold as well. Furthermore, the affected skin may have persistent color changes, sweat glands can be affected, lost nails do not always grow back, and affected joints can become achy and stiff.

Frostbite is a severe condition and is best avoided by preventing prolonged cold exposure. If you do develop frostbite, you should seek immediate medical attention for appropriate rewarming and further evaluation and care.

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